2.80 Geotropism

- Geo = gravity, tropic = growth response
- An example: seed:
- the embryonic roots grow downwards, this is described as positive geotropism
- the embryonic shoot will grow upwards, this is negative geotropism

- Further experiment: take the same germinating seed and rotating it anti-clockwise to face upwards.
- The shoot grow upwards showing negative geotropism
- The roots will grow downwards showing positive geotropism

2.53 Uptake of Water

- Root hairs are made of epidermal cells
- Minerals go into the plant by active transport
- Water goes into the root hair by osmosis
- The cell wall expands, therefore, there is more surface area for osmosis to occur
- The xylem transports the minerals and water up the roots and through the whole plant